.jshintrc

schemes: fix a broken check for drive letter conflicts

Flagged by pytype locally.  It appears to have regressed in 1863584f2fba (not
yet released).

This seems like an obvious typo- `dict.isalpha()` is nonsense.  There's no crash
though because `schemes` is pre-populated with 5 schemes (that are all now
defunct), so the length of the dict is never 1, so it's impossible to abort.

{
    // Enforcing
    "eqeqeq"        : true,     // true: Require triple equals (===) for comparison
    "forin"         : true,     // true: Require filtering for..in loops with obj.hasOwnProperty()
    "freeze"        : true,     // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
    "nonbsp"        : true,     // true: Prohibit "non-breaking whitespace" characters.
    "undef"         : true,     // true: Require all non-global variables to be declared (prevents global leaks)

    // Environments
    "browser"       : true      // Web Browser (window, document, etc)
}